Electric bipost lamp adaptor



June 17, 1947. Q CARROLL 2,422,222

ELECTRIC BI-POST LAMP ADAPTOR Fi-led June 14, 1944 'INVENTOR. J/wmasla wall I ATTORNEY Patented June 17, 1947 UNITED STATES PATENT 1 OFFICE 3 Claims.

This invention relates to an improved electric lamp adaptor and more particularly to a suitable adaptor which enables large bi-post incandescent lamps to be used with Edison screw shell lamp socket fixtures, whereby existing installations of such fixtures may be utilized either for Edison screw base lamps or bi-post lamps.

In general, electric lighting fiixtures for offices, stores and homes comprise the conventional Edison screw-shell socket type of receptacles adapted to receive incandescent lamps with screw-shell bases. As the lamps were increased in size to meet increasing light demands in oflices, factories and the like, incandescent lamps of higher wattage, for example, from 300 to 1,000 Watts, were developed, and with these larger lamps the screw shell socket could be employed, the diameter of such sockets depending upon the diameter of the lamp bases employed, one of these larger types of sockets being generally known in the trade as the Mogul type screw base socket. More recently, in an effort to provide a more efiicient type in the larger sizes of incandescent lamps, there has been developed the bi-post lamp which employs an incandescent coiled filament that depends below a flared deflecting screen secured to the arbor or filament supporting structure, the screen serving to increase the efficiency of the lamp and give a better distribution of the light pattern emitted. In the latter type of lamp, and particularly in those of larger sizes, the heat developed due to the degree of incandescence of its light emitting elements is extremely high. It has been found undesirable to employ a screw type base with these lamps, since such a base conducts so much heat to the socket when the lamp is burning that it causes overheating of the socket. This overheating tends to cause the base of the lamp to swell and freeze into the shell of the socket and often causes the base and shell to become fused or welded to each other. This freezing or welding action frequently is so severe that the glass envelope of the lamp would break when attempts were made to remove the lamp, thus making the remaining metal base of the lamp even more diflicult to remove from the socket, and there also existed the likelihood of the glassenvelope breaking and causing injury to the person attempting to remove it.

In order to obviate these and other difficulties resulting from their high operating temperatures, the newer type of lamps at present employs a bi-post construction which constists of two sturdy steel or other hard metal posts of cylindrical configuration which project from the base of the lamp, and a special, type of bayonet-catch socket and contact structure is employed for receiving the lamps. The connections from the lamps to the supply leads comprise the metal posts and electrical spring-pressed switch contact members composed of brass leaf spring contacts to avoid overheating of the connecting parts. The posts or prongs of the bi-post lamp are usually coated with a thin layer of carbon to prevent fusing or welding of the prongs to the brass leaf spring contacts.

A serious objection "to the use of the -bi-'post lamps lies in the fact that the conventional screw-shell sockets present in existing installations cannot accommodate the bi-post lamps, and when it is desired to use such lamps it is necessary to change out, existing fixtures and install a special type of socket for receiving the bi-post structure, which is not adapted to receive Edison base lamps. This entails considerable wastage and expense in replacing the fixtures, and the electricians time necessary to effect the change-over operations. Moreover, in certain locations or for certain purposes it may be desirable to use the conventional-Edison base lamps, while in other adjacent locations or for other purposes the bi-post type of lamp is preferable, and it may be desirable to use both types of lamps either in adjacent locations or alternatively in the same fixtures.

One of the objects of the invention is an improved electric lamp adaptor which obviates the foregoing disadvantages and costs attendant to changing over lamp fixtures from the Edison screw base type to a. type adapted to receive bipost lamps.

Another object is an electric lamp adaptor which enables either Edison base lamps or bipost lamps to be used with existing screw-shell lamp socket fixtures.

A further object is an adaptor of the type described in which various of the parts thereof conform generally to parts now employed in commercial types of lamp sockets, and which requires no substantial departure f-rom established designs and methods of manufacture and assembly.

A still further object of the invention is an adaptor which increases the spacing between a bi-post type of lamp and the receiving receptacle so as to minimize the eifect of heat on the receptacle; more specifically, in one embodiment means are provided for thermally insulating-certain of the parts of the adaptor from each other engaged from each other for clarity;

Fig. 2 is an end View of the adaptor looking in the direction of the arrows 2-2 in Fig. 1, showing bayonet type slots for receiving the connecting posts of the bi-post lamp;

Fig. 3 is a sectional view of the adaptor looking in the direction of the arrows 3--3 in Fig. 1,

with certain portions of the adaptor broken away;

Fig. 4 is a cross-sectional View taken along the line 4-4 of Fig. 3;

Fig. 5 is a cross-sectional view taken along the line 5-5 of Fig. 3; and

Fig. 6 is a fragmentary detail of a fastening means employed for mechanically securing the body portions of the adaptor to each other.

Referring now to Fig. 1, there is shown a conventional Edison base screw socket which com prises a body 'I of porcelain or other suitable insulating material. The socket may be either a Mogul or medium type, and has an inner brass screw shell which ordinarily receives a screw base lamp or plug. A central contact spring 9 is mounted in the body I for connection with the central conducting stud of a lamp or plug when inserted in the socket. The socket is secured in any suitable manner to an outlet fixture, as by a bracket or condulet Ill which is screwed to the end of a conduit II. Conductors I2 in the conduit connect the shell 8 and spring contact 9 to the lighting circuit.

,The bi-post adaptor comprises, in the illustrative embodiment illustrated, an upper circular body I5 of porcelain or other refractory insulating material, and a lower circular body I6 of similar material. On the upper body is secured, by

screws I8, a screw base I! of brass or other suitable metal, adapted to be received within the screw shell socket 8. The body I5 also has a projecting portion I5a, Figs. 1 and 3, which seats a center contact 2| of brass, Figs. 3 and 4, the contact being secured by a screw 22 which also serves to connect contact 2 I, through the medium.

of a metal connecting strip 23, with a conductor 24 within the body pieces I5 and I6. tact 2| is adapted to engage the spring contact 9 of the socket I when the adaptor is screwed into the socket. The base I! is electrically connected,

through the medium of the screws I8 and an arcuate conducting strip I9, to a conductor 253 within the body pieces. These conductors are soldered, brazed or otherwise electrically and me-' chanically connected to their respective interme-.

32 and nuts 34 serving to firmly secure the bodies I5 and I6 together to form a unitary device. Preferably, and as shown, a circular gasket 35 of asbestos or other good heat insulating material The con-' 4 is interposed and clamped between the porcelain pieces I5 and I6 thereby to thermally insulate to a substantial extent the bodies from each other. This reduces thermal conduction through the porcelain pieces and minimizes the amount of heat conducted to the brass shell I1, which heat tends to cause freezing or welding of the shell to the socket.

Referring now to the bi-post incandescent lamp shown in the lower portion of Fig. 1, this comprises a glass envelop 49, having two connecting posts 4! with shoulder portions Mb which are mounted in the press of the lamp and are connected by depending lead-in conductors 42, 42 to the coil filament 45 of tungsten or other suitable material which emits a brilliant light when heated to incandescence. The conductors 42, 42 also support the arbor structure comprising insulating rods 43, 4t and 5'! which support a deflecting screen at and the filament 45. The posts M are adapted to enter flexible bayonet slot.,re-.

ceiving members of spring steel, Fig. 2, contained within the adaptor body. The spring members 58, and as the lamp is rotated through a small angle, in a clockwise direction asviewed in Fig. 2, the shoulders formed by the reduced portion am of the lamp posts engage the, edges of the curved bayonet slots and flex the members 55 slightly to provide firm engagement of the upper end of the lamp envelope with the lower rim 3? of the adaptor, thereby to firmly secure or look the lamp in proper position in the adaptor.

The electrical connection between the lamp and adaptor is provided by setsof curved brass contact springs 52, Fig. 5, which are engagedby the lamp posts 5! when the lamp is inserted and rotated in the adaptor, as above described. Usually the posts M of a bi-post lamp have a thin coating of carbon thereon to prevent fusing or welding of the posts to the contact springs.

Curved clamping members 53 of spring steel serve to apply the proper resilient pressure to the contact springs. connected by metal straps 5d and connecting screws 55, Fig. 3, to the conductors 2E) and 24 the straps 54% being secured to the body It by screws 55.

In addition to the thermal insulating features:

above mentioned, the adapter increases the distance between the lamp and screw basesocket, and this further reduces theheating effect on the socket and its connecting parts. While the adap tor is shown as comprising two porcelain body pieces l5 and it, it may be made of one body piece, in which case the internal connections may be simplified to provide one-piece conductors each between the members I! and 2! and the contact springs 52.

Various other modifications and changes may readily be suggested to those versed in the art without departing from the principle of the invention disclosed, and I therefore do not wish to be limited except as indicated by the scope of the appended claims. 7

I claim:

1. An adaptor unit for connecting a bi-post connecting structure thereon adapted .to 'be screwed into said receptacle, another insulating The sets of contact springs are body piece having a bayonet type socket structure embodied therein for receiving the bi-post lamp, said socket structure having clamping contact clips for engagement with the sides of the contact posts of said lamp when inserted therein and bayonet type slotted members for receiving and engaging said posts and locking the lamp in the adaptor when it is inserted therein and turned to cause engagement of the lamp posts in said slotted spring members, metallic means for clamping the body pieces together to form a unitary structure, and conductors passing through said body pieces for connecting said screw plug structure with said contact springs, said clamping means for the body pieces being electrically insulated from the live portions of the currentcarrying elements of the adaptor unit.

2. An adaptor unit for connecting a bi-post lamp to a screw shell receptacle, comprising an insulating body piece having metallic screw plug connecting structure thereon adapted to be screwed into said receptacle, another insulating body piece having a bayonet type socket structure embodied therein for receiving the bi-post lamp, said socket structure having clamping contact clips for engagement with the sides of the contact posts of said lamp when inserted therein and bayonet type slotted members for receiving and engaging said posts and locking the lamp in the adaptor when it is inserted therein and turned to cause engagement of the lamp posts in said slotted spring members, means comprising metal rings respectively engaging said body pieces for clamping the pieces to ether to form a unitary structure, and conductors passing through said body pieces for connecting said screw plug structure with said contact springs.

3. An adaptor unit for connecting a bi-post lamp to a screw shell receptacle, comprising an insulating body piece having metallic screw plug connecting structure thereon adapted to be screwed into said receptacle, another insulating body piece having a bayonet type socket structure embodied therein for receiving the bi-post lamp, said socket structure having clamping contact clips for engagement with the sides of the contact posts of said lamp when inserted therein and bayonet type slotted spring members for receiving and engaging said posts and locking the lamp in the adaptor when it is inserted therein and turned to cause engagement of the lamp posts in said slotted spring members, means for clamp- REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,349,097 Kennelly May 16, 1944 1,336,608 Benjamin Apr. 13, 1920 1,584,303 Kaynor May 11, 1926 2,098,080 Wright Nov. 2, 1937 2,105,884 I-Ianser Jan. 18, 1938 

